Office 15 and Zune: Separated at Birth?

I was looking at Office 15 on a normal desktop computer with a large screen, and two things stand out that weren't obvious on a tablet. One, the Office 15 applications look an awful lot like the Zune PC software. Are they based on the same technologies? Or is this is just a "Metro-like" look and feel thing?

Consider this screenshot to see what I mean:

Second, and perhaps more oddly, the Office 15 apps dispense with a shadow when in windowed mode. But they have a weird color-code halo instead, as you can see below. This is only present when the Office application is the foreground applications. I find it distracting.

(For some reason, the OneNote ribbon doesn't appear on the tablet. But it shows up on the desktop PC. Clearly, more testing is in order here.)